Reversing valve for fluid compressors



SePt- 27, 1932. y B. H. THOMPSON 1,879,647

REVERSING VALVE FLUID COMPRESSORS `A Filed Nov. 4, 1930 E@ 1123.2 Q l lo n A uw" www1 30 42?;2 BENJAMIN H.TH0MPsoN Patented Sept. 27, 1932 UNITED STATE/s Mir- ENi oja-1er.;

BENJ'lfIN H. THOMPSON, OF .ELE-BABA, PFNNSYLVANA, ASSIGNOR T0 THE WESTING- HOUSE AIR BRAKE COMPANY, OF 0F PENNSYLVANIA WILMERDING, PENNSYLVANIA, A CORPORATION Applicationy led November 4, 193Q. Serial No.493,340. v

T his invention relates to uid compressors and more particularly to the type employed on locomotives in railroad service.

The locomotive type of fluid compressor comprises a main valve device for controlling the admission of steam to and its exhaust from the steam cylinders of the compressor, a reversing valve for controlling the operation of the main valve device and a reversing rod operated by the movement of a steam piston for operating the reversingvalve. Vl/iith this type of compressor, diiiiculty has been' encountered, under certain conditions of operation, in obtaining full-reverse movement of the reversing valve which prevents the compressor pistons from moving their full stroke. Y

@ne object of my invention is to provide an improved reversing valve construction in which apiston type of reversing valve is employed. l Another object of myl invention is to provide an improved reversing valve, the movement of which is initiated of the movement of the steam piston, but completed by the pressure of steam.

Another object of my invention is to provide an improved reversing valve which is positive in operation and which will quickly move to its full reverse position. y

Other objects and advantageswill appear in the following more detailed description of my invention.

In the accompanying drawing; Figure 1 is a diagrammatic view, mainly in section, of a luid compressor embodying my improved construction of reversing valve; Fig. 2 is an enlarged sectional view of a portion of the compressor shown in Fig. 1 and including the reversing valve; Fig. 3 is a diagrammaticY purpose of illustration, said compressor comprising an air compressor portion 1, a steam motor Aportion 2, an intermediate section 3 to which the air compressor portion 1 and motor portion 2 aresecured, an air valve portion 4 which forms a cover plate for the f lower end of the compressor portion v1 and a portion 5 which forms a cover plate for the upper end of, the motor portion2.` Y y The motorA portion 2 contains a high pressure steam piston 6 which is connected to a low pressure air piston 7 in the compressor portion 1 by means of a rod 8 for operating said air piston. A low'p-ressure steam piston 9 is also contained in the motor portion 2 and is connected by a rod 10 to a high pressure air piston 11 in the compressor portion 1 for operating said air piston.

The portion 5 comprises a main valve for controlling the admission of steam to and its enhaust from the opposite sides ofthe steam pistons 6 and 9, and a reversing valve 19 for which is intermediate the areas of pistons 12 and 14, all of said pistons being operatively connected tog'ether.`

The reversing valve 19 comprises a hollow member having formed at its upper end a pistonhead 2O and at its lower end piston heads 21 and 22 and intermediate the two ends a piston head 23.` The piston heads 20, 21 and 22 are each of the same area, but the piston h ead 23is of larger area. Y

Disposed inthe casing is a bushing 24 having a bore in its lower end for receivingthe piston heads v21 and 22, and abore in its upper end of larger diameter for receiving the larger piston head 23. A cap 25..A having screw-threaded engagement in the casing for closing the upper open end of the bushing24 is provided with a bushing 26 for receiving the piston yhead 20. 1

The reversing valve 19 is mounted' on 'a reversing rod 32 and atone endengages aV conical shaped seat 28 formed on an enlarged portion of said rod. The reversing rod is pistony 12 and having at l' loc Vso

provided with an extension 29 which loosely extends through a bore 30 and chamber 31 in said reversing valve and which is provided with an enlarged guide section 33 adapted to have a sliding fit in a bore in the upper end of the reversing valve. A nut 34 having screwthreaded engagement with'the outer end of extension 29 is provided for securing the reversing valve between the seat 28 and a washer 35 interposed betweensaid nut and the upper end of said reversing valve.

The chamber 36 below the reversing valve 19 is open to the chamber above' the steam piston 6 through an aperture 37 in the end wall of the bushing 24. Passage 38 inthe seat 28 connects chamber 36 to bore 30 and passage 39 connects the bore -30 through chamber 31 to chamber 40 abovel the reversing valve, so that steam pressure above the steam piston 6 acts in chamber 40 on the piston head 20 as well as in chamber 36 on piston head 21. A passage 41 is provided through the wall of the reversing valve to connect the cavity 42 between piston heads 21 and 22 to cavity 43 between piston heads 2O and 23. y

In operation, assuming the reversing valve 19 and main valve to be initially in the positions shown in Fig. 1, steam from pipe 44 is supplied through passage 45 to chamber 46 between the reversing valve piston heads 22 and 23, and iows from said chamber through passage 47' to chamber 13 and acts on the main valve piston 12. Steam is also supplied from passage 45 through passage 50 to chamber 51 between the main valve pistons 12 and 18,

and to chamber 52 between the main valve pistons 14 and 16, and from chamber 51 steam flows4 through passage 53 to the chamber above the steam piston 6.` The chamber below the steam piston 6 is connected tothe chamber at the lower side of the low pressure steam piston 9 through passage 54, chamber 55 between the main valve pistons 16 and 17 and passage 56. The chamber at the lowerA side of the low pressure steam piston 9 is initially at atmospheric pressure, but during operation, the steam from the lower sideof the. high pressure steam piston 6 is permitted to expand into said low pressure piston chamber and under either circumstance, the high pressure steam acting above the steam piston 6 moves said piston downwardlyagainst the lower pressure acting below said piston.

When the high pressure steamv piston 6 nears the end of its downward stroke, the button574 on the reversing rod 32 is engaged by a striker plate 58 carried by said piston and the .reversing rod is pulled downwardly which starts a downward movement of the reversing valve 19.

YArs the reversing valve is moved downwardly bythe piston 6 acting through the reversing rod, the piston head 23 moves over the steam supply passage 45 and connectssaid passage to chamber 43 between piston heads 23 and 20, and at substantially the same time, the chamber 46 between the piston heads 23 and 22 is connected to passage 48 leading to the exhaust pipe 49. The pressure of steam in chamber 43 acting on the dierential area of piston head 23 then shifts the reversing valve 19 downwardly to the full reverse position shown in Figs. 3 and 4, against theexhaust pressure in chamber 46. It will be noted that the reversing valve 19 is moved initially by the steam` piston 6 acting through the reversing rod 32, but the final movement of the reversing valve kis eected by the pressure of the supply steam and therefore is independent of the piston 6.

In the lower position of the reversing valve 19, the main valve piston chamber 13 is opened to the atmosphere through passage 59, chamber-46 around the reversing valve, passage 48 and pipe 49. The pressure of steam -in the main valve piston chamber 51 acting on the differential area of piston 12 then shifts the main valve pistons to the position shownxin Fig. `3 of the drawing, iny which positionthechamber below the low pressure air piston 9 is connectedto the atmosphere through passage 56, chamber 55 betweenthe main valve pistons 16.and 17, passage 48 and pipe 49.V The chamber at the upper side of the low pressure steam piston 9 is connected to the chamber at the upper side of the high pressure steam piston 6 through passage y60, chamber 61 between the main valve pistons 17 and 18 and passage 53, which permits the steam above the high pressure piston to expand into the chamber at the upper sidefof the low pressure piston 9 and move the low pressure steam piston 9 downwardly.

Steam supplied from pipe 44 through passage 45 and passage 50 to chamber 52 between the main valvepistons 14 and 16 ows Jfrom said chamber throughpassage 54 to the chamber below the high pressure steam piston v6 and moves said piston upwardly against the reduced pressure of steam in the chamber above said piston.A

When the high pressure steam piston 6 nears the end of its upward stroke, the striker plate 58 on said piston engages the shoulder 62 on the reversingv rod and starts the reversing rod and reversing valve 19 moving upwardly. As soon as the reversing valve piston head 23 moves past the passage 45, steam is supplied to chamber 46'between the piston heads 23 and 22 and at substantially the same time, chamber 43 between piston heads 20 and 23 is connected to the atmosphere through passage 41 in the reversing valve, chamber 42 between piston heads 22 and 21, passage 48 and exhaust pipe 49. The pressure of. supply steam in chamber 46 acting on the differential .area of piston 23, then shifts the reversing valve 19 upwardly to the full reverse position` shown in Figs. 1 and 2 against the opposing exhaust pressure in chamber 43 and it will be noted that this final upward movement of the reversing valve is independent of the movement of pist-on 6.

In the upper position of the reversing valve 19, steam is again supplied from passage 45 through chamber 46 to passage 47 through which it flows to the main valve piston chamber 18. With the main valve piston chamber 15 open to the exhaust passage 48, the steam pressure acting in chamber 13 on the piston 12 moves the main valve pistons to the position shown in Fig. 1.

After a certain predetermined movement of the main valve piston 12 toward the position shown in Fig. 1, the passage 59 is uncovered through which steam is also supplied to chamber 13 for insuring prompt and comlcte reverse movement of the main valve. `iassage 47 is preferably provided with a restricted portion for throttling the initial supply of steam to the main valve piston chamber 13 so as to start the main valve moving gradually after which an unrestricted supply of steam to said chamber is provided through passage 59.

With the mam valve 1n the position shown in TEig. 1, another cycle of operation 1s started and the compressor operates 1n the same manner as hereinbefore described.

It will be noted that the reversing valve piston head 28 in addition to moving the reversing valve 19 to its reverse position also cooperates with the piston 22 in forming a valve which controls the supply of steam to and its exhaust from the main valve piston chamber 13 for controlling the operation of the main valve.

`While one illustrative embodiment of the invention has been described in detail, it is not my intention to limit its scope to that embodiment or otherwise than by the terms of the appended claims.

Having now described my invention, what I claim as new and desire to secure by Letters Patent, is:

1. In a steam engine, the combination with a steam actuated p-iston, and a steam actuated valve device for controlling the steam for operating said piston, of a reversing valve means comprising a plurality of connected piston heads, one of which is of greater area than the others and cooperates with one of the others for controlling the steam for operating said valve device, and a reversing rod carried by said reversing valve means and operatively connected to said piston.

2. In a steam engine, the combination with a steam actuated piston, and a steam actuated valve device for controlling the steam for operating said piston, of a reversing valve means for controlling the steam for operating said valve device and comprising differential area pistons for operating said valve means, and a reversing rod carried b'y said reversing valve means through which said reversing valve means is adapted to be operated by said piston.

3. In asteam engine, the combination with asteam actuated piston, and` asteam actuated valve device or controlling'th'e steam from a supplyfor operating said piston, of a reversing valve means movable to two positions for controlling the supply of steamto said valve device, and means carried by said reversing valve means and operable by said piston for initiating the :movement of said reversing. valve means, said reversing valve means comprising4 a plurality of connected pistons, one of saidpistons being of greater area than the others .and subject to the pressure lor steam from said supply for completingvthe movement of said reversing valve means and for holding same-in the reverse position. f

4. A reversing valve construction forza steam engine comprising a casing having a bore, the inner portion of which is of smaller diameter than the outer portion, la reversing valve having four connected piston heads two of which are adapted to operate in the inner portion of said boreand a third of which is adapted to operate in the outer portion of said bore, a member adapted to be secured to said casing and having` a` bore for receiving the fourth piston head, and a reversing rod secured to said reversing valve for operating said reversing valve.

5. A reversing valve construction for a steam engine comprising a reversing valve having four connected piston heads and an annular chamber between each pair of said piston heads and provided with a longitudinal bore, a passage at one end of said reversing` valve connecting said b-cre to the outer face of one of the end piston heads, a reversing rod of smaller area than said bore and extending therethrough, a passage through said reversing rod connecting said bore to the outer face of the other of the end piston heads, and a passage in said reversing valve connecting the annular chambers between each of the outer piston heads and their adjacent piston hea 6. In a steam engine, the combination with a steam actuated piston, and a valve device for controlling the supply of steam for operating said piston, of a reversing valve means for controlling the operation of said valve device and having differential piston heads operable by variations in steam pressure for moving said valve means, said reversing valve means being adapted to vary the'steam pressure on said piston heads upon movement of said reversing valve means, and means operated by said piston for initially moving said reversing valve means.

7. In a steam engine, the combination with a steam actuated piston having a chamber at oiie side,4 anclal valve device for control'-v ling thesupply of steam to and its exhaust from said chamber and having a control chamber alternately supplied with steam and vented for effecting the operation of said valve device, oa reversing valve means comprising two connected'piston heads of diierent areas for controlling the supply of steam to and its'venting. from said control chamber7 means'for maintaining 'equal pressures on therouter' face of each of said pis tons, a third piston head .connected to one of the above mentioned piston heads and subject on its outer face to the pressure in the irst mentioned chamber, a ifourth piston head` secured. to the other of the first mentionedpiston heads, means for establishing communication between the outer Jfaces of the third and fourth mentioned piston heads,

Y and a reversing rod operatively connecting said reversing valve means to said steam actuated piston.r

In testimony whereof I have hereunto set my hand this 30th day of October, 1930.

i BENJAMIN H. THOMPSON.

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